CCTV played in court has shown a former soldier visiting a garden centre with his family hours before he murdered his ex-girlfriend, her mother and her sister.
Kyle Clifford, 26, was also filmed in a branch of B&Q days earlier on 4 July last year buying the silver duct tape he would use to restrain former partner Louise Hunt during the attack.
He has admitted murdering the 25-year-old, her mother Carol Hunt, 61, and Louise's sister Hannah Hunt, 28, at the family home, where they lived with BBC racing commentator John Hunt, in Bushey, Hertfordshire, on 9 July last year.
Clifford has also admitted possession of the butcher's knife used to kill Mrs Hunt and the crossbow used to shoot her daughters, as well as false imprisonment of Louise.
He has chosen not to attend his trial at Cambridge Crown Court for a single charge of raping Louise, which he denies.
Prosecutors say Clifford started planning the four-hour attack against her and members of her family after she broke up with him 13 days earlier.
Jurors were played footage of Clifford lifting weights at a gym on 5 July.
Another clip shows him arriving at a garden centre near his home in Enfield, north London, with members of his family shortly before 10am on the day of the murders.
Detective Constable Alex Leckie said he was there with his mother, father and niece, and at one point he can be seen pushing a buggy.
Further footage showed Clifford, dressed all in black, parking his car near the Hunt family home before walking to the address and knocking on the door shortly after 2.30pm.
A doorbell camera captured his conversation with Carol Hunt as he told her he was "just dropping off some of Louise's stuff".
Mrs Hunt asks how he is and he replies: "I'm good, thank you. What's wrong? You look like…"
"I've seen a ghost," she responds.
Mr Hunt watched proceedings from the public gallery, while a woman left in tears after the footage at the doorstep was played.
Prosecutors say Clifford took a bag of clothes and a "thank you" card as a "ruse" to get inside the house before taking a knife from his backpack to kill her.
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Another CCTV clip shows him leaving the house before returning with the crossbow hidden under a blanket and letting himself back into the house with a key.
He is said to have held Louise for hours after she returned from working at her dog grooming business, which she ran from a pod in the garden, then shot her moments before her sister got home.
The court heard in a 999 call to police, Hannah Hunt said: "My sister's ex-boyfriend has come in and he shot us."
She was found found collapsed in the doorway when emergency services arrived but died shortly after.
The trial continues.
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